Polycarbodiimide has been conventionally utilized as an adhesive or a sealing material for an electronic material component or the like because of having high adhesiveness and heat resistance. Such polycarbodiimide is cast in the state of a solution, and thus utilized as an adhesive or a sealing material. Such polycarbodiimide can also be utilized as a curing agent of a resin composition such as a photo-sensitive resin composition and a curing type aqueous resin composition. Polycarbodiimide, however, has the problems of being low in solubility in various solvents, and also being difficult to store for a long period even in a cold dark place because the state of a solution thereof causes a reaction of a carbodiimide group and aggregation of a polymer to gradually progress, thereby forming gel.
In order to solve such problems, there is known, as a conventional art, a modified polycarbodiimide compound that has very excellent storage stability due to modification of polycarbodiimide derived from an aromatic diisocyanate compound with diisopropylamine (see, for example, PTL1). The modified carbodiimide compound, when cast and then dried, re-produces a carbodiimide group by amine dissociation, thereby exhibiting more excellent adhesiveness or the like. In addition, the modified carbodiimide compound, when used as a curing agent of a resin composition, re-produces a carbodiimide group by amine dissociation during drying, and the carbodiimide group allows a resin composition to be cured.